This invention relates generally to medical methods and apparatus, and more particularly, to methods and apparatus for the endovascular or minimally invasive surgical repair of atrioventricular valves of the heart, including the mitral valve and the tricuspid valve.
The heart includes four valves that direct blood through the two sides of the heart. The mitral valve lies between the left atrium and the left ventricle and controls the flow of blood into the left side of the heart. The valve includes two leaflets, an anterior leaflet and a posterior leaflet, that close during systole. The leaflets are passive in that they open and close in response to pressure induced to the leaflets by the pumping of the heart. More specifically, during a normal cycle of heart contraction (systole), the mitral valve functions as a check valve to prevent the flow of oxygenated blood back into the left atrium. In this manner, oxygenated blood is pumped into the aorta through the aortic valve.
Occasionally, the mitral valve is formed abnormally through a congenital condition. More often, however, the mitral valve degenerates with age. Among the problems that can develop is mitral valve regurgitation in which the mitral valve leaflets become unable to close properly during systole, thus enabling leakage to flow through the mitral valve during systole. Over time, regurgitation of the mitral valve can adversely affect cardiac function and may compromise a patient's quality of life and/or life-span.
Mitral valve regurgitation can result from a number of different mechanical defects in the mitral valve. For example, the valve leaflets, the valve chordae which connect the leaflets to the papillary muscles, or the papillary muscles themselves may become damaged or otherwise dysfunctional. Moreover, the valve annulus may become damaged or weakened and may limit the ability of the mitral valve to close adequately during systole.
Known treatments for mitral valve regurgitation commonly rely on valve replacement or annuloplasty, or strengthening of the mitral valve through surgical repairs and/or implanting a mechanical structure within the mitral valve. For example, the most prevalent and widely accepted known techniques to correct mitral valve regurgitation, repair the mitral valve via open heart surgery. During such an invasive surgical procedure, it is known to suture adjacent segments of the opposed valve leaflets together in a procedure known as a “bow-tie” or “edge-to-edge” surgical technique. Although each of the afore-mentioned treatments can be effective, generally known treatments rely on open heart surgery wherein the patient's chest is opened and the patient's heart is stopped while the patient is place on a cardiopulmonary bypass. The need to open the patient's chest and to place the patient on a cardiopulmonary bypass creates inherent risks that may be traumatic to the patient.
Percutaneously treatments are less invasive than the treatments mentioned above, but such treatments may be less effective and more difficult to effect repair because of the limited amount of space in and around the mitral valve in which to maneuver a repair device or devices. For example, U.S. Pat. No. 6,875,224 to Grimes describes a percutaneous mitral valve repair method in which the opposed leaflets are each immobilized to enable the two leaflets to be fastened together. Furthermore, U.S. Pat. No. 6,6290,534 to St. Goar et al. describes a plurality of embodiments for use in endovascular repair of cardiac valves in which, in each embodiment, both leaflets are grasped and held firmly in position prior to permanent treatment. However, grasping both leaflets while the patient's heart is beating may be a time-consuming and laborious task that demands a coordinated effort on the part of the surgical team. Moreover, to facilitate grasping both leaflets percutaneously may require that the patient's heart be temporarily stopped or slowed by drugs or other techniques. Slowing and/or stopping the patient's heart during surgery may increase the risks to the patient.